:) Cell Division And Cellular.Organisms Flashcards
What are the stages of the cell cycle?
Synthesis Gap phase 1 G1 checkpoint M phase Gap phase 2 G2 checkpoint Synthesis
G2 checkpoint
Cell checks whether all DNA has been replicated without any damage
If it had the cell can enter mitosis
M phase
Mitosis (nuclear division) and cytokinesis
(Cytoplasmic division) Metaphase checkpoint
Gap phase 1
Cell grows and new organelles and proteins are made
G1 checkpoint
Cell checks that the chemicals needed for replication are present and for any damage to the DNA before entering S-phase
Gap phase 2
Cell keeps growing and proteins needed for cell division are made
Synthesis
Cell replicated its DNA ready to divide by mitosis
When does the cell cycle start and end?
Starts When a cell has been produced by cell division
Ends with cell dividing to produce two identical cell
What does the cell cycle consist of?
Period of cell growth and DNA replication (interphase)
Periods of cell division (M phase)
What is interphase subdivided into?
Cell growth
Subdivided into three different separate growth stages
G1, s and G2
How is the cell cycle regulated?
By checkpoints that occur at key points during a cycle to make sure it’s okay for the process to continue
What is mitosis needed for?
The growth of multicellular organisms (like us)
Repairing damaged tissues
Method of asexual reproduction for some plants, animals and fungi
What is mitosis really?
One continuous process
Series of division phases: prophase, metaphase, anaphase and telophase
When does interphase happen?
Before mitosis in the fell cycle
When the cell grows and replicates their DNA ready for division
Describe interphase
Cell carried out normal functions and prepares to divide
Cells DNA is unraveled and replicated to double its genetic content
Organelles replicated so it has spare ones
ATP is increased (ATP provides energy needed for cell division)
Describe prophase?
Chromosomes condense getting shorter and fatter
Tiny bundled of protein (centrioles) start moving to opposite ends of cell forming network of protein fibres (spindle)
Nuclear envelope breaks down and chromosomes lie free in the cytoplasm
What is the cell cycle? The
The process that all body cells in multicellular organisms use to grow and divide
What are the chromosomes made of when mitosis begins?
Two strands joined in the middle by a centromere. The separate strands are called chromatids
Why are there two strands?
Each chromosome has already made an indentical copy of itself during interphase. When mitosis is over, chromatids, end up as one-strand chromosome in the new daughter cells
Describe metaphase
Chromosomes (each with two chromatids) line up along the middle of the cell and become attached to the spindle by their centromere.
What happens at the metaphase checkpoint
The cell checks that all the chromosomes are attached to the spindle before mitosis can continue
Anaphase describe
Centromeres divide separating each pair of sister chromatids. The spindle contracts, pulling chromatids to opposite ends of the cell, centromere first.
Telophase
Chromatids reach opposite poles in the spindle. They uncoil and become long and thin again. Called chromosomes again. Nuclear envelope forms around each group of chromosomes so there are two nuclei
Cytokinesis
Cytoplasm divides in animal cells a cleavage furrow forms to divide the cell membrane. There are now two daughter cells that are genetically identical to the original cell to each other. Cytokinesis usually begins in anaphase and ends in telophase.
Separate process to mitosis